Herbicidal fluorobenzothiazolyloxyacetamides

ABSTRACT

Novel herbicidal fluorobenzothiazolyloxyacetamides of the formula ##STR1## in which R 1  represents hydrogen or an optionally substituted radical from the group consisting of alkyl, alkenyl, alkinyl and aralkyl, 
     R 2  represents an optionally substituted radical from the group consisting of alkyl, alkenyl, alkinyl, cycloalkyl, cycloalkenyl, aralkyl, aryl, alkoxy, alkenyloxy or alkinyloxy, or 
     R 1  and R 2 , together with the nitrogen atom to which they are bonded, form an optionally substituted, saturated or unsaturated nitrogen heterocycle which can contain further heteroatoms and to which a benzo group can be fused.

This is a division of application Ser. No. 08/119,462, filed Sep. 9,1993, now U.S. Pat. No. 5,356,864.

It has already been disclosed that certain benzothiazolyloxyacetamides,such as, for example, N-methylbenzothiazolyloxyacetanilide haveherbicidal properties (cf. EP-A-5,501; U.S. Pat. No. 4,509,971, U.S.Pat. No. 4,784,682 and U.S. Pat. No. 4,833,243). However, the herbicidalactivity of these known compounds is not always completely satisfactory.

New fluorobenzothiazolyloxyacetamides have now been found of the generalformula (I) ##STR2## in which R¹ represents hydrogen or an optionallysubstituted radical from the group consisting of alkyl, alkenyl, alkinyland aralkyl,

R² represents an optionally substituted radical from the groupconsisting of alkyl, alkenyl, alkinyl, cycloalkyl, cycloalkenyl,aralkyl, aryl, alkoxy, alkenyloxy or alkinyloxy, or

R¹ and R², together with the nitrogen atom to which they are bonded,form an optionally substituted, saturated or unsaturated nitrogenheterocycle which can contain further heteroatoms and to which a benzogroup can be fused.

It has further been found that the new fluorobenzothiazolyloxyacetamidesof the formula (I) are obtained when fluorobenzothiazoles of the generalformula (II) ##STR3## in which X represents halogen or alkylsulphonyl,

are reacted with hydroxyacetamides of the general formula (III) ##STR4##in which R¹ and R² have the abovementioned meanings,

if appropriate in the presence of a diluent, if appropriate in thepresence of an acid-binding agent and if appropriate in the presence ofa catalyst.

Finally, it has been found that the newfluorobenzothiazolyloxyacetamides of the general formula (I) haveinteresting herbicidal properties.

Surprisingly, the compounds of the formula (I) according to theinvention show, in some cases with very good tolerability to cropplants, such as, for example, rice, considerably stronger action againstpoorly controllable weeds, such as, for example, barnyard grass(Echinochloa crus galli) than the chemically similar known compoundN-methylbenzothiazolyloxyacetanilide.

The invention preferably relates to compounds of the formula (I) inwhich

R¹ represents hydrogen, C₁ -C₈ -alkyl (which is optionally substitutedby fluorine, chlorine, cyano or C₁ -C₄ -alkoxy), C₂ -C₈ -alkenyl (whichis optionally substituted by fluorine and/or chlorine), C₂ -C₈ -alkinylor benzyl,

R² represents C₁ -C₈ -alkyl (which is optionally substituted byfluorine, chlorine, cyano or C₁ -C₄ -alkoxy), C₂ -C₈ -alkenyl (which isoptionally substituted by fluorine and/or chlorine), C₂ -C₈ -alkinyl, C₃-C₆ -cycloalkyl (which is optionally substituted by chlorine and/or C₁-C₃ -alkyl) , C₅ - or C₆ -cycloalkenyl, benzyl (which is optionallysubstituted by fluorine, chlorine and/or C₁ -C₄ -alkyl), phenyl (whichis optionally substituted by fluorine, chlorine, bromine, iodine, cyano,nitro, C₁ -C₄ -alkyl, trifluoromethyl, C₁ -C₄ -alkoxy and/or C₁ -C₄-alkylthio), C₁ -C₈ -alkoxy (which is optionally substituted by C₁ -C₄-alkoxy) or C₃ -C₄ -alkenyloxy, or

R¹ and R², together with the nitrogen atom to which they are bonded,form an optionally saturated or unsaturated five- to seven-memberednitrogen heterocycle which is monosubstituted to trisubstituted by C₁-C₃ -alkyl and optionally benzo-fused.

The invention relates in particular to compounds of the formula (I) inwhich

R¹ represents C₁ -C₄ -alkyl, allyl or propargyl,

R² represents C₁ -C₆ -alkyl, C₁ -C₂ -alkoxy-C₁ -C₂ -alkyl, allyl,propargyl, cyclopentyl, cyclohexyl, cyclohexenyl, benzyl, phenyl (whichis optionally substituted by fluorine, chlorine, bromine, cyano, nitro,methyl, ethyl, trifluoromethyl, methoxy or ethoxy), C₁ -C₆ -alkoxy or C₁-C₂ -alkoxy-C₁ -C₂ -alkoxy, or

R¹ and R², together with the nitrogen atom to which they are bonded,represent piperidinyl which is optionally monosubstituted totrisubstituted by methyl and/or ethyl, pyrrolidinyl which is optionallymonosubstituted or disubstituted by methyl and/or ethyl,perhydroazepinyl or 1,2,3,4-tetrahydro(iso)quinolyl.

Very particularly preferred groups of compounds of the formula (I) areillustrated below by the formulae (IA), (IB), (IC) and (ID), where R¹and R² have the meanings indicated above as preferred or as particularlypreferred. ##STR5##

The abovementioned definitions or explanations of radicals, which aregeneral or mentioned in ranges of preference, correspondingly apply tothe final products and to the starting materials and intermediates.These definitions of radicals can be combined with one another in anydesired manner, i.e. also between the respective ranges of preference.

Examples of the possible meanings of the group ##STR6## in the formulae(I), (IA), (IB), (IC) and (ID) are shown in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Examples of the meaning of the group                                           ##STR7##                                                                     ______________________________________                                         ##STR8##                                                                                       ##STR9##                                                    ______________________________________                                        N(CH.sub.3).sub.2                                                                              N(C.sub.4 H.sub.9).sub.2                                     N(C.sub.2 H.sub.5).sub.2                                                                       N(CH.sub.2 CHCH.sub.2).sub.2                                 N(C.sub.3 H.sub.7).sub.2                                                                        ##STR10##                                                    ##STR11##                                                                                      ##STR12##                                                    ##STR13##                                                                                      ##STR14##                                                    ##STR15##                                                                                      ##STR16##                                                    ##STR17##                                                                                      ##STR18##                                                    ##STR19##                                                                                      ##STR20##                                                    ##STR21##                                                                                      ##STR22##                                                    ##STR23##                                                                                      ##STR24##                                                    ##STR25##                                                                                      ##STR26##                                                    ##STR27##                                                                                      ##STR28##                                                    ##STR29##                                                                                      ##STR30##                                                    ##STR31##                                                                                      ##STR32##                                                    ##STR33##                                                                                      ##STR34##                                                    ##STR35##                                                                                      ##STR36##                                                    ##STR37##                                                                                      ##STR38##                                                    ##STR39##                                                                                      ##STR40##                                                    ##STR41##                                                                                      ##STR42##                                                    ##STR43##                                                                                      ##STR44##                                                    ##STR45##                                                                                      ##STR46##                                                    ##STR47##                                                                                      ##STR48##                                                    ##STR49##                                                                                      ##STR50##                                                    ##STR51##                                                                                      ##STR52##                                                    ##STR53##                                                                                      ##STR54##                                                    ##STR55##                                                                                      ##STR56##                                                    ##STR57##                                                                                      ##STR58##                                                    ##STR59##                                                                                      ##STR60##                                                    ##STR61##                                                                                      ##STR62##                                                    ##STR63##                                                                                      ##STR64##                                                    ##STR65##                                                                                      ##STR66##                                                    ##STR67##                                                                                      ##STR68##                                                    ##STR69##                                                                                      ##STR70##                                                    ##STR71##                                                                                      ##STR72##                                                    ##STR73##                                                                                      ##STR74##                                                    ##STR75##                                                                                      ##STR76##                                                    ##STR77##                                                                                      ##STR78##                                                    ##STR79##                                                                                      ##STR80##                                                    ##STR81##                                                                                      ##STR82##                                                    ##STR83##                                                                                      ##STR84##                                                    ##STR85##                                                                                      ##STR86##                                                    ##STR87##                                                                                      ##STR88##                                                    ##STR89##                                                                                      ##STR90##                                                    ##STR91##       N(CH.sub.2 CH.sub.2 CN).sub.2                                 ##STR92##                                                                                      ##STR93##                                                    ##STR94##                                                                                      ##STR95##                                                    ##STR96##                                                                                      ##STR97##                                                    ##STR98##                                                                                      ##STR99##                                                    ##STR100##                                                                                     ##STR101##                                                   ##STR102##                                                                                     ##STR103##                                                   ##STR104##                                                                                     ##STR105##                                                   ##STR106##                                                                                     ##STR107##                                                   ##STR108##                                                                                     ##STR109##                                                   ##STR110##                                                                   ______________________________________                                    

If, for example, 2-chloro-6-fluoro-benzothiazole andN,N-diethyl-hydroxyacetamide are used as starting substances, the courseof the reaction in the preparation process according to the inventioncan be represented by the following reaction scheme: ##STR111##

Formula (II) provides a general definition of the fluorobenzothiazolesto be used as starting substances in the process according to theinvention for the preparation of the compounds of the formula (I).

In formula (II), X preferably represents fluorine, chlorine or bromineas well as C₁ -C₄ -alkylsulphonyl, in particular chlorine ormethylsulphonyl.

With the exception of 2,6-difluoro-benzothiazole and2-chloro-6-fluoro-benzothiazole (cf. Org. Magn. Reson, 7 (1975),84-85--cited in Chem. Abstracts 83:113186x), the starting substances ofthe formula (II) are not yet known from the literature and, with theexception of the two known compounds mentioned, are--as newsubstances--also a subject of the present invention.

Examples of the new compounds of the formula (II) which may be mentionedare:

2-Chloro-4-fluoro-benzothiazole, 2-chloro-5-fluoro-benzothiazole,2-chloro-7-fluoro-benzothiazole,2-methylsulphonyl-4-fluoro-benzothiazole,2-methylsulphonyl-5-fluoro-benzothiazole,2-methylsulphonyl-6-fluorobenzothiazole and2-methylsulphonyl-7-fluoro-benzothiazole.

The fluorobenzothiazoles of the general formula (II) are obtained when

(a) in the case in which X represents halogen,2-amino-fluorobenzothiazoles of the general formula (IV) ##STR112## arereacted with diazotising and halogenating agents, such as, for example,sodium nitrite, hydrochloric acid and copper powder, at temperaturesbetween -10° C. and +60 ° C. (cf. the preparation examples).

The 2-amino-fluorobenzothiazoles of the formula (IV) are known and/orcan be prepared by processes known per se (cf. J. Chem. Soc. C 1969,268-272; J. Heterocycl. Chem. 18 (1981), 759-761; Synthet. Commun. 17(1987), 229-240; EP-A 282971; preparation examples).

The fluorobenzothiazoles of the formula (II) are also obtained when

(b) in the case in which X represents halogen,2-mercapto-fluorobenzothiazoles of the general formula (V) ##STR113##are reacted with halogenating agents, such as, for example, thionylchloride, if appropriate in the presence of reaction auxiliaries, suchas, for example, dimethylformamide, at temperatures between 0° C. and100° C. (cf. the preparation examples), or when

(c) in the case in which X represents alkylsulphonyl,2-mercapto-fluorobenzothiazoles of the formula (V) are reacted withalkylating agents, such as, for example, methyl iodide, if appropriatein the presence of acid-binding agents, such as, for example, sodiumhydroxide and in the presence of diluents, such as, for example, water,at temperatures between -10° C. and +100° C. and the alkylation productsobtained in this way are reacted with oxidising agents, such as, forexample, hydrogen peroxide, if appropriate in the presence of reactionauxiliaries, such as, for example, formic acid, sulphuric acid andammonium molybdate, at temperatures between 0° C. and 50° C. (cf. thepreparation examples).

The 2-mercapto-fluorobenzothiazoles of the formula (V) are known and/orcan be prepared by processes which are known per se (cf. DE-OS (GermanPublished Specification) 3,008,225; U.S. Pat. No. 4,873,346; preparationexamples).

Formula (III) provides a general definition of the hydroxyacetamidesfurther to be used as starting substances in the process according tothe invention for the preparation of compounds of the formula (I).

In formula (III), R¹ and R² preferably or in particular have thosemeanings which have already been indicated above as preferred or asparticularly preferred for R¹ and R² in connection with the descriptionof the compounds of the formula (I) according to the invention.

The hydroxyacetamides of the formula (III) are known and/or can beprepared by processes known per se (cf. U.S. Pat. No. 4,509,971 and U.S.Pat. No. 4,645,525; also U.S. Pat. No. 4,334,073, DE-OS (GermanPublished Specification) 3,038,598, DE-OS (German PublishedSpecification) 3,038,636, EP-A-37,526, EP-A-348,737 and DE-OS (GermanPublished Specification) 3,819,477).

The process according to the invention for the preparation of the newfluorobenzothiazolyloxyacetamides of the formula (I) is preferablycarried out using diluents. These preferably include hydrocarbons, suchas, for example, toluene, xylene or cyclohexane, halogeno-hydrocarbons,such as, for example, methylene chloride, ethylene chloride, chloroformor chlorobenzene, ethers, such as, for example, diethyl ether, dipropylether, diisopropyl ether, dibutyl ether, diisobutyl ether, glycoldimethyl ether, tetrahydrofuran and dioxane, alcohols, such as, forexample, methanol, ethanol, propanol, isopropanol, butanol, isobutanol,sec-butanol or tert-butanol, ketones, such as, for example, acetone,methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone,esters, such as, for example, methyl acetate and ethyl acetate, amides,such as, for example, dimethylformamide, dimethylacetamide, andN-methylpyrrolidone, nitriles, such as, for example, acetonitrile andpropionitrile, sulphoxides, such as, for example, dimethyl sulphoxideand also water or aqueous salt solutions.

The salts used here are preferably chlorides or sulphates of alkalimetals or alkaline earth metals, such as, for example, sodium chloride,potassium chloride or calcium chloride. Sodium chloride is particularlypreferred.

The process according to the invention is advantageously carried outusing acid-binding agents. Those which are preferably used are stronglybasic alkali metal and alkaline earth metal compounds, for exampleoxides, such as, for example, sodium oxide, potassium oxide, magnesiumoxide and calcium oxide, hydroxides, such as, for example, sodiumhydroxide, potassium hydroxide, magnesium hydroxide and calciumhydroxide, alkoxides, such as, for example, sodium tert-butoxide andpotassium tert-butoxide and/or carbonates, such as, for example, sodiumcarbonate, potassium carbonate, magnesium carbonate and calciumcarbonate.

The addition of 0.01 to 10% by weight (relative to glycolic acid amideof the formula (III) employed of a phase transfer catalyst may in somecases prove advantageous. Examples of such catalysts which may bementioned are:

Tetrabutylammonium chloride, tetrabutylammonium bromide,tributyl-methylphosphonium bromide, trimethyl-C₁₃ /C₁₅ -alkyl-ammoniumchloride, dibenzyl-dimethyl-ammonium methylsulphate, dimethyl-C₁₂ /C₁₄-alkyl-benzylammonium chloride, tetrabutylammonium hydroxide,18-crown-6, triethylbenzylammonium chloride, trimethylbenzylammoniumchloride, tetraethylammonium bromide.

The reaction temperatures in the process according to the invention canbe varied within a relatively wide range. In general, the reaction iscarried out at temperatures between -50° C. and +110° C., preferably attemperatures between -20° C. and +80° C.

The process according to the invention is in general carried out atnormal pressure, but it can also be carried out at elevated or reducedpressure, for example between 0.1 and 10 bar.

To carry out the process according to the invention, 0.5 to 5 mol,preferably 0.8 to 1.5 mol, of hydroxyacetamide of the formula (III) arein general employed per mole of fluorobenzothiazole of the formula (II).The reaction components can be mixed together in any desired sequence.The reaction mixture is in each case stirred until the end of thereaction and worked up according to customary methods (cf. thepreparation examples).

The active compounds according to the invention can be used asdefoliants, desiccants, agents for destroying broad-leaved plants and,especially, as weed-killers. By weeds, in the broadest sense, there areto be understood all plants which grow in locations where they areundesired. Whether the substances according to the invention act astotal or selective herbicides depends essentially on the amount used.

The active compounds according to the invention can be used, forexample, in connection with the following plants:

Dicotyledon weeds of the genera: Sinapis, Lepidium, Galium, Stellaria,Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio,Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, polygonum,Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Rotala,Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeopsis,Papaver, Centaurea, Trifolium, Ranunculus and Taraxacum.

Dicotyledon cultures of the genera: Gossypium, Glycine, Beta, Daucus,Phaseolus, Pisum, Solanum, Linum, Ipomoea, Vicia, Nicotiana,Lycopersicon, Arachis, Brassica, Lactuca, Cucumis and Cucurbita.

Monocotyledon weeds of the genera: Echinochloa, Setaria, Panicum,Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus,Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristylis,Sagittaria, Eleocharis, Scirpus, Paspalum, Ischaemum, Sphenoclea,Dactyloctenium, Agrostis, Alopecurus and Apera.

Monocotyledon cultures of the genera: Oryza, Zea, Triticum, Hordeum,Avena, Secale, Sorghum, Panicurn, Saccharum, Ananas, Asparagus andAllium.

However, the use of the active compounds according to the invention isin no way restricted to these genera, but also extends in the samemanner to other plants.

The compounds are suitable, depending on the concentration, for thetotal combating of weeds, for example on industrial terrain and railtracks, and on paths and squares with or without tree plantings.Equally, the compounds can be employed for combating weeds in perennialcultures, for example afforestations, decorative tree plantings,orchards, vineyards, citrus groves, nut orchards, banana plantations,coffee plantations, tea plantations, rubber plantations, oil palmplantations, cocoa plantations, soft fruit plantings and hopfields, onlawns, turf and pasture land, and for the selective combating of weedsin annual cultures.

The compounds of the formula (I) according to the invention areparticularly suitable for the selective control of monocotyledon weeds,such as, for example, barnyard grass (Echinochloa crus galli) intransplanted rice. However, they can also be employed generally for thecontrol of monocotyledon weeds in dicotyledon crop plants populations.

The active compounds can be converted into the customary formulations,such as solutions, emulsions, suspensions, powders, foams, pastes,granules, aerosols, natural and synthetic materials impregnated withactive compound, and very fine capsules in polymeric substances.

These formulations are produced in a known manner, for example by mixingthe active compounds with extenders, that is liquid solvents, liquifiedgases under pressure and/or solid carriers, optionally with the use ofsurface-active agents, that is emulsifying agents and/or dispersingagents and/or foam-forming agents.

In the case of the use of water as an extender, organic solvents can,for example, also be used as auxiliary solvents. As liquid solvents,there are suitable in the main: aromatics, such as xylene, toluene oralkylnaphthalenes, chlorinated aromatics or chlorinated aliphatichydrocarbons, such as chlorobenzenes, chloroethylenes or methylenechloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, forexample petroleum fractions, mineral and vegetable oils, alcohols, suchas butanol or glycol as well as their ethers and esters, ketones, suchas acetone, methyl ethyl ketone, methyl isobutyl ketone orcyclohexanone, strongly polar solvents, such as dimethylformamide anddimethyl sulphoxide, as well as water.

As solid carriers there are suitable: for example ammonium salts andground natural minerals, such as kaolins, clays, talc, chalk, quartz,attapulgite, montmorillonite or diatomaceous earth, and ground syntheticminerals, such as highly disperse silica, alumina and silicates; assolid carriers for granules there are suitable: for example crushed andfractionated natural minerals such as calcite, marble, pumice, sepioliteand dolomite, as well as synthetic granules of inorganic and organicmeals, and granules of organic material such as sawdust, coconut shells,maize cobs and tobacco stalks; as emulsifying and/or foamforming agentsthere are suitable: for example non-ionic and anionic emulsifiers, suchas polyoxyethylene fatty acid esters, polyoxyethylene fatty alcoholethers, for example alkylaryl polyglycol ethers, alkylsulphonates, alkylsulphates, arylsulphonates as well as albumen hydrolysis products; asdispersing agents there are suitable: for example lignin-sulphite wasteliquors and methylcellulose.

Adhesives such as carboxymethylcellulose and natural and syntheticpolymers in the form of powders, granules or latexes, such as gumarabic, polyvinyl alcohol and polyvinyl acetate, as well as naturalphospholipids, such as cephalins and lecithins, and syntheticphospholipids, can be used in the formulations. Further additives can bemineral and vegetable oils.

It is possible to use colorants such as inorganic pigments, for exampleiron oxide, titanium oxide and Prussian Blue, and organic dyestuffs,such as alizarin dyestuffs, azo dyestuffs and metal phthalocyaninedyestuffs, and trace nutrients such as salts of iron, manganese, boron,copper, cobalt, molybdenum and zinc.

The formulations in general contain between 0.1 and 95 percent by weightof active compound, preferably between 0.5 and 90%.

For controlling weeds, the active compounds according to the invention,as such or in the form of their formulations, can also be used asmixtures with known herbicides, finished formulations or tank mixesbeing possible.

Suitable herbicides for the mixtures are known herbicides, for exampleanilides such as, for example, diflufenican and propanil; arylcarboxylicacids such as, for example, dichloropicolinic acid, dicamba andpicloram; aryloxyalkanoic acids such as, for example, 2,4 D, 2,4 DB, 2,4DP, fluroxypyr, MCPA, MCPP and triclopyr; aryloxy-phenoxy-alkanoicesters such as, for example, diclofop-methyl, fenoxaprop-ethyl,fluazifop-butyl, haloxyfop-methyl and quizalofop-ethyl; azinones suchas, for example, chloridazon and norflurazon; carbamates such as, forexample, chlorpropham, desmedipham, phenmedipham and propham;chloroacetanilides such as, for example, alachlor, acetochlor,butachlor, metazachlor, metolachlor, pretilachlor and propachlor;dinitroanilines such as, for example, oryzalin, pendimethalin andtrifluralin; diphenyl ethers such as, for example, acifluorfen, bifenox,fluoroglycofen, fomesafen, halosafen, lactofen and oxyfluorfen; ureassuch as, for example, chlortoluron, diuron, fluometuron, isoproturon,linuron and methabenzthiazuron; hydroxylamines such as, for example,alloxydim, clethodim, cycloxydim, sethoxydim and tralkoxydim;imidazolinones such as, for example, imazethapyr, imazamethabenz,imazapyr and imazaquin; nitriles such as, for example, bromoxynil,dichlobenil and ioxynil; oxyacetamides such as, for example, mefenacet;sulphonylureas such as, for example, amidosulfuron, bensulfuron-methyl,chlorimuron-ethyl, chlorsulfuron, cinosulfuron, metsulfuron-methyl,nicosulfuron, primisulfuron, pyrazosulfuron-ethyl,thifensulfuron-methyl, triasulfuron and tribenuron-methyl; thiocarbamtessuch as, for example, butylate, cycloate, di-allate, EPTC, esprocarb,molinate, prosulfocarb, thiobencarb and triallate; triazines such as,for example, atrazine, cyanazine, simazine, simetryne, terbutryne andterbutyiazine; triazinones such as, for example, hexazinone, metamitronand metribuzin; others such as, for example, aminotriazole, benfuresate,bentazone, cinmethylin, clomazone, clopyralid, difenzoquat, dithiopyr,ethofumesate, fluorochloridone, glufosinate, glyphosate, isoxaben,pyridate, quinchlorac, quinmerac, sulphosate and tridiphane.

A mixture with other known active compounds, such as fungicides,insecticides, acaricides, nematicides, bird repellants, plant nutrientsand agents which improve soil structure, is also possible.

The active compounds can be used as such, in the form of theirformulations or in the use forms prepared therefrom by further dilution,such as ready-to-use solutions, suspensions, emulsions, powders, pastesand granules. They are used in the customary manner, for example bywatering, spraying, atomizing or scattering.

The active compounds according to the invention can be applied eitherbefore or after emergence of the plants. They can also be incorporatedinto the soil before sowing.

The amount of active compound used can vary within a substantial range.It depends essentially on the nature of the desired effect. In general,the amounts used are between 10 g and 10 kg of active compound perhectare of soil surface, preferably between 50 g and 5 kg per ha.

The preparation and use of the active compounds according to theinvention can be seen from the following examples.

PREPARATION EXAMPLES Example 1 ##STR114##

A solution of 0.6 g (15 mmol) of sodium hydroxide in 2.7 ml of water isadded dropwise with stirring at 20° C. to a mixture of 2.5 g (15 mmol)of N-methyl-hydroxyacetanilide, 3.5 g (15 mmol) of2-methylsulphonyl-4-fluorobenzothiazole and 50 ml of acetone. Thereaction mixture is stirred at 20° C. for 12 hours and then poured intoabout twice the volume of water. The product obtained in crystallineform in this way is isolated by filtering off with suction.

3.8 g (79% of theory) ofN-methyl-α-(4-fluoro-benzothiazol-2-yl-oxy)-acetanilide of melting point94° C. are obtained.

Example 2 ##STR115##

A solution of 3.75 g (16.6 mmol) of 2-chloro-7-fluorobenzothiazole in 20ml of acetonitrile is added dropwise with stirring to a mixture, cooledto -10° C., of 2.74 g (16.6 mmol) of N-methyl-hydroxyacetanilide, 0.93 g(16.6 mmol) of potassium hydroxide and 50 ml of isopropanol. Thereaction mixture is stirred at 0° C. to 5° C. for 6 hours, then pouredinto about twice the volume of water and extracted three times withmethylene chloride. The combined organic phases are washed with water,dried with sodium sulphate and filtered. After concentration of thefiltrate, the residue is purified by column chromatography two times (1.silica gel/methylene chloride, 2. silica gel/methyl tert-butyl ether).

1.4 g (27% of theory) ofN-methyl-α-(7-fluoro-benzothiazol-2-yl-oxy)-acetanilide of melting point116° C. are obtained.

The compounds of the formula (I): ##STR116## shown in Table 2 below canalso be prepared, for example, analogously to Examples 1 and 2 andcorresponding to the general description of the preparation processaccording to the invention.

                                      TABLE 2                                     __________________________________________________________________________    Preparation Examples of the compounds of the formula (I)                                                        Melting                                        Po-                            point (°C.)                          Ex.                                                                              sition                         (refractive                                 No.                                                                              of F                                                                             R.sup.1  R.sup.2            index)                                      __________________________________________________________________________     3 5  CH.sub.3                                                                                ##STR117##        144                                          4 5  CH(CH.sub.3).sub.2                                                                      ##STR118##        115                                          5 5  CH(CH.sub.3).sub.2                                                                      ##STR119##        113                                          6 5  CH.sub.3                                                                                ##STR120##        115                                          7 5  CH.sub.3                                                                                ##STR121##        146                                          8 5  (CH.sub.2).sub.6            114                                          9 5  C.sub.2 H.sub.5                                                                         ##STR122##         97                                         10 5  CH.sub.3 n-C.sub.4 H.sub.9   53                                         11 5  CH.sub.2 CHCH.sub.2                                                                    CH.sub.2 CHCH.sub.2                                                                              (n.sub.D .sup.20 : 1.5345)                  12 5  CH.sub.3                                                                                ##STR123##         92                                         13 6  CH(CH.sub.3).sub.2                                                                      ##STR124##         72                                         14 6  CH(CH.sub.3).sub.2                                                                      ##STR125##        108                                         15 6  CH.sub.3                                                                                ##STR126##         83                                         16 6  C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5    65                                          17 6  CH(CH.sub.3)(CH.sub.2).sub.5                                                                              (n.sub.D .sup.20 : 1.5510)                  18 6  CH(CH.sub.3).sub.2                                                                     OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                                (n.sub.D .sup.20 : 1.5128)                  19 6  (CH.sub.2).sub.6             55                                         20 6  CH(CH.sub.3).sub.2                                                                     OCH(CH.sub.3).sub.2                                                                               46                                         21 6  CH.sub.2 CHCH.sub.2                                                                    CH.sub.2 CHCH.sub.2                                                                               68                                         22 6  CH.sub.3 CH(CH.sub.3)C.sub.2 H.sub.5                                                                       69                                         23 6                                                                                 ##STR127##                                                                             ##STR128##         89                                         24 6  n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9  (n.sub.D .sup.20 : 1.5321)                  25 6  CH.sub.3 n-C.sub.4 H.sub.9   66                                         26 6  CH(CH.sub.3).sub.2                                                                      ##STR129##         86                                         27 5  CH(CH.sub.3).sub.2                                                                      ##STR130##        125                                         28 5                                                                                 ##STR131##                                                                             ##STR132##        128                                         29 7  CH(CH.sub.3).sub.2                                                                      ##STR133##        107                                         30 5  CH(CH.sub.3).sub.2                                                                     OCH(CH.sub.3).sub.2                                                                              (n.sub. D .sup.20 : 1.5372)                 31 5  CH(CH.sub.3).sub.2                                                                     OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                                (n.sub.D .sup.20 : 1.5365)                  32 5  CH.sub.2 CH(CH.sub.3)(CH.sub.2).sub.3                                                                     64                                          33 4  CH(CH.sub.3).sub.2                                                                      ##STR134##        92                                          34 4  CH(CH.sub.3).sub.2                                                                      ##STR135##         76                                         35 4  CH.sub.3                                                                                ##STR136##        145                                         36 4  CH.sub.3                                                                                ##STR137##         86                                         37 4  CH.sub.2 CHCH.sub.2                                                                    CH.sub.2 CHCH.sub.2                                                                               56                                         38 4  CH(CH.sub.3).sub.2                                                                     OC.sub.2 H.sub.4 OC.sub.2 H.sub.5                                                                (n.sub.D .sup.20 : 1.4991)                  39 7  CH(CH.sub.3).sub.2                                                                      ##STR138##        108                                         40 7  CH(CH.sub.3).sub.2                                                                     OC.sub.2 H.sub. 4 OC.sub.2 H.sub.5                                                                46                                         41 7  CH(CH.sub.3).sub.2                                                                     OCH(CH.sub.3).sub.2                                                                               41                                         42 7  CH.sub.3                                                                                ##STR139##        121                                         43 7  CH.sub.3                                                                                ##STR140##        104                                         44 7  CH.sub.3 n-C.sub.4 H.sub.9   61                                         45 7  (CH.sub.2).sub.6            88                                          46 7  CH.sub.3                                                                                ##STR141##        99                                          47 7  CH(CH.sub.3).sub.2                                                                      ##STR142##        113                                         48 7  CH.sub.2 CHCH.sub.2                                                                    CH.sub.2 CHCH.sub.2                                                                               56                                         49 5  CH.sub.3 CH(CH.sub.3)C.sub.2 H.sub.5                                                                      (n.sub.D .sup.20 : 1.5305)                  50 5  CH(CH.sub.3).sub.2                                                                     n-C.sub.6 H.sub.13 (n.sub.D .sup.20 : 1.5208)                  51 5  CH(CH.sub.3).sub.2                                                                     CH.sub.2 CH.sub.2 CH(CH.sub.3).sub.2                                                             (n.sub.D .sup.20 : 1.5035)                  52 5  C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5    (n.sub.D .sup.20 : 1.5395)                  53 5  CH.sub.2 CH(C.sub.2 H.sub.5)(CH.sub.2).sub.3                                                              (n.sub.D .sup.20 : 1.5465)                  54 5  CH(CH.sub.3).sub.2                                                                      ##STR143##        102                                         55 5  n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9   42                                         56 5  n-C.sub.3 H.sub.7                                                                      n-C.sub.3 H.sub.7   60                                         57 5  CH(CH.sub.3)(CH.sub.2).sub.4                                                                               96                                         58 4  CH(CH.sub.3).sub.2                                                                      ##STR144##        138                                         59 4  CH(CH.sub.3).sub.2                                                                     OCH(CH.sub.3).sub.2                                                                               52                                         60 4  n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9   34                                         61 4  (CH.sub.2).sub.6             75                                         62 4  CH.sub.2 CH(C.sub.2 H.sub.5)(CH.sub.2).sub.3                                                              (n.sub.D .sup.20 : 1.5032)                  63 4  CH.sub.3 CH(CH.sub.3)C.sub.2 H.sub.5                                                                       72                                         64 4  n-C.sub.3 H.sub.7                                                                      n-C.sub.3 H.sub.7   49                                         65 4  CH(CH.sub.3)(CH.sub.2).sub.4                                                                               67                                         66 4  C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5     73                                         67 4  C.sub.2 H.sub.5                                                                         ##STR145##        100                                         68 6  CH.sub.3                                                                                ##STR146##        113                                         69 5  CH(CH.sub.3).sub.2                                                                     CH.sub.2 CH(CH.sub.3)CH(CH.sub.3)C.sub.2 H.sub.5                                                 (n.sub.D .sup.20 : 1.5246)                  70 5  n-C.sub.3 H.sub.7                                                                      CH.sub.2 CH(C.sub.2 H.sub.5).sub.2                                                               (n.sub.D .sup.20 : 1.5132)                  71 6  CH.sub.3                                                                                ##STR147##        148                                         72 6  CH.sub.2 CH(C.sub.2 H.sub.5)(CH.sub.2).sub.3                                                              (n.sub.D .sup.20 : 1.5088)                  73 6  n-C.sub.3 H.sub.7                                                                      n-C.sub.3 H.sub.7  (n.sub.D .sup.20 : 1.5391)                  74 7  n-C.sub.4 H.sub.9                                                                      n-C.sub.4 H.sub.9  (n.sub.D .sup.20 : 1.5095)                  75 7  CH(CH.sub.3).sub.2                                                                      ##STR148##         84                                         76 7  n-C.sub.3 H.sub.7                                                                      n-C.sub.3 H.sub.7   70                                         77 7  CH(CH.sub.3)(CH.sub.2).sub.4                                                                               88                                         78 7  CH.sub.3 CH(CH.sub.3)C.sub.2 H.sub.5                                                                       49                                         79 7  C.sub.2 H.sub.5                                                                         ##STR149##         92                                         80 6  C.sub.2 H.sub.5                                                                         ##STR150##        107                                         81 7  CH.sub.2 CH(C.sub.2 H.sub.5)(CH.sub.2).sub.3                                                               60                                         82 7  C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5     45                                         83 4  CH.sub.3                                                                                ##STR151##         84                                         84 5  CH.sub.3                                                                                ##STR152##         85                                         85 7  CH.sub.3                                                                                ##STR153##         96                                         86 4  C.sub.2 H.sub.5                                                                         ##STR154##        107                                         87 7  C.sub.2 H.sub.5                                                                         ##STR155##        119                                         88 5  C.sub.2 H.sub.5                                                                         ##STR156##        116                                         __________________________________________________________________________

STARTING SUBSTANCES OF THE FORMULA (II) Example (II-1) ##STR157##

A mixture of 300 g (2.67 mol) of 3-fluoro-aniline, 271 g (2.67 mol) ofconc. hydrochloric acid and 259 g (2.67 mol) of potassium thiocyanate isheated under reflux for 6 hours. After cooling, the product, which isobtained in crystalline form, is isolated by filtering off with suction.

190 g (41.5% of theory) of N-(3-fluoro-phenyl)-thiourea of melting point109° C. are obtained. ##STR158##

A solution of 176 g (1.1 mol) of bromine in 190 ml of chloroform isadded dropwise with stirring to a solution, cooled to 0° C., of 190 g(1.1 mol) of N-(3-fluorophenyl)thiourea in 1100 ml of chloroform and thereaction mixture is then heated under reflux for 4 hours. It is thenconcentrated, the residue is taken up in 3 liters of water and themixture is adjusted to pH=1 with conc. sulphuric acid. It is thenfiltered and the filtrate is rendered alkaline with conc. ammonia. Theproduct, which is obtained in crystalline form, is isolated by filteringoff with suction.

147 g (70% of theory) of 2-amino-5-fluoro-benzothiazole of melting point167° C. are obtained. ##STR159##

A solution of 242 g (3.5 mol) of sodium nitrite in 440 ml of water isadded dropwise with stirring to a mixture, cooled to -10° C., of 147 g(0.87 mol) of 2-amino-5-fluorobenzothiazole, 1700 ml of conc.hydrochloric acid and 20 g of copper power and the reaction mixture isstirred at 0° C. for 60 minutes and at 50° C. for a further 60 minutes.It is then extracted with chloroform and the solvent is carefullyremoved by distillation from the organic phase in a water-jet vacuum.

80 g (49% of theory) of 2-chloro-5-fluoro-benzothiazole are obtained asa crystalline residue of melting point 69° C.

Example (II-2 ) ##STR160##

A mixture of 12.9 g (0.1 mol) of 2,3-difluoroaniline and 30 ml ofdimethylformamide is heated to reflux and at the same time a solution of48 g (0.3 mol) of potassium ethyl xanthate in 80 ml of dimethylformamideis added dropwise in the course of 1 hour. The bottom temperature iskept at 145° C. by removal of distillate. The reaction mixture isstirred under reflux for 15 hours and poured into 1 liter of water aftercooling. It is then acidified at 10° C. with a solution of 20 ml ofconc. hydrochloric acid in 30 ml of water and the crystalline product isisolated by filtering off with suction.

18.0 g (87% of theory) of 2-mercapto-7-fluorobenzothiazole of meltingpoint 193° C. are obtained. ##STR161##

9.3 g (44.5 mmol) of 2-mercapto-7-fluoro-benzothiazole are added to 50ml of thionyl chloride and, after addition of 1 ml of dimethylformamide,the mixture is slowly heated to reflux. After stirring under reflux forone hour, the mixture is cooled and concentrated in a water-jet vacuum.The residue is taken up in methylene chloride, washed with water, driedwith sodium sulphate and filtered. The filtrate is concentrated and theresidue is purified by column chromatography (silica gel/methylenechloride).

4.3 g (45% of theory) of 2-chloro-7-fluoro-benzothiazole are obtained asa yellow oil.

Example (II-3) ##STR162##

A mixture of 97 g (0.75 mol) of 2,6-difluoroaniline, 120 g (0.75 mol) ofpotassium ethyl xanthate and 750 ml of dimethyl sulphoxide is stirred at120° C. for 3 hours. After cooling, it is diluted with 300 ml of waterand adjusted to pH=1 with conc. hydrochloric acid. The product which isobtained in crystalline form in this way is isolated by filtering offwith suction.

120 g (80% of theory) of 2-mercapto-4-fluorobenzothiazole of meltingpoint 180° C. are obtained. ##STR163##

111 g (0.77 mol) of methyl iodide are added dropwise with stirring to amixture, cooled to 0° C., of 120 g (0.65 mol) of2-mercapto-4-fluoro-benzothiazole, 26 g (0.65 mol) of sodium hydroxideand 750 ml of water. The reaction mixture is stirred for 3 hours and theproduct, which is obtained in crystalline form, is isolated by filteringoff with suction.

51 g (39% of theory) of 2-methylthio-4-fluoro-benzothiazole of meltingpoint 30° C. are obtained. ##STR164##

145 ml of a 35% strength aqueous hydrogen peroxide solution (1.7 mol ofH₂ O₂) are added dropwise with stirring to a mixture, kept at 30° C., of51 g (0.25 mol) of 2-methylthio-4-fluoro-benzothiazole, 500 ml ofchloroform, 25 ml of formic acid and 2.5 ml of conc. sulphuric acid andalso 2 g of ammonium molybdate. The reaction mixture is stirred at 30°C. for 2 hours and the product, which is obtained in crystalline form,is isolated by filtering off with suction.

31 g (54% of theory) of 2-methylsulphonyl-4-fluorobenzothiazole ofmelting point 160° C. are obtained.

2-Methylsulphonyl-7-fluoro-benzothiazole of the formula below, forexample, is also obtained analogously to Example (II-3) via2-mercapto-7-fluoro-benzothiazole and2-methylthio-7-fluoro-benzothiazole. ##STR165##

USE EXAMPLES

The compound shown below is used as a comparison substance in thefollowing use examples: ##STR166##N-methylbenzothiazol-2-yl-oxyacetanilide (mefenacet) (disclosed inEP-A-5,501, Ex. 1)

Example A Pre-emergence Water Surface Treatment in Transplanted PaddyRice

To prepare an applicable preparation, 1 part of active compound isdissolved using 5 parts of acetone; 1 part of benzyloxy polyglycol etheris then added as an emulsifier. Water is then added to the desiredconcentration. Rice in the 2-3 leaf stage is transplanted into potswhich are filled with soil. Seeds of test plants are sown (1 cm deep).Two days later, the pots are flooded with 3 cm of water. The activecompound preparations are then applied to the water surface. 4 weekslater, the herbicidal action and the damage to the treated plants isassessed visually in % in comparison to untreated plants. 0% denotes noeffect, 100% denotes complete destruction.

In this test, the in part very good tolerability of the active compoundsaccording to the invention--in particular the compounds from PreparationExamples (3), (4), (5), (6) and (7)--is seen in rice together withsubstantially more powerful action against weeds in comparison with theknown compound (A), in particular against barnyard grass (Echinochloacrus galli).--The compound from Preparation Example (39) acts in thesame way.

Example B Pre-emergence Test

Solvent: 5 parts by weight of acetone

Emulsifier: 1 part by weight of alkylaryl polyglycol ether

To produce a suitable preparation of active compound, 1 part by weightof active compound is mixed with the stated amount of solvent, thestated amount of emulsifier is added and the concentrate is diluted withwater to the desired concentration.

Seeds of the test plants are sown in normal soil and, after 24 hours,watered with the preparation of the active compound. It is expedient tokeep constant the amount of water per unit area. The concentration ofthe active compound in the preparation is of no importance, only theamount of active compound applied per unit area being decisive. Afterthree weeks, the degree of damage to the plants is rated in % damage incomparison to the development of the untreated control. The figuresdenote:

0%=no action (like untreated control)

100%=total destruction

In this test, the compounds according to Preparation Examples (2), (4),(5), (6) and (7) show powerful action against weeds, together with goodtolerability for crop plants, such as, for example, soya.--here again,compound (39) acts in analogous manner.

It will be appreciated that the instant specification and claims are setforth by way of illustration and not limitation, and that variousmodifications and changes may be made without departing from the spiritand scope of the present invention.

We claim:
 1. A fluorobenzothiazole of the formula ##STR167## in which Xrepresents C₁₋₄ -alkylsulphonyl.
 2. A compound according to claim 1, inwhich X represents methylsulphonyl.